Explosive growth of data services of terminals gradually tensions existing network resources particularly under the condition that network layout of a new-generation communication technology (such as 3rd-Generation (3G) and Long-Term Evolution (LTE)) may not be widely implemented, which consequently causes incapability in meeting requirements of users on rate and traffic and poorer user experiences.
Except a wireless network technology provided by the 3rd Generation Partnership Project (3GPP), a Wireless Local Area Network (WLAN) which has been widely applied at present, particularly an Institute of Electrical and Electronics Engineers 802.11 (IEEE802.11)-standard-based WLAN, has been widely applied to hotspot access coverage in homes, enterprises and even the Internet. A technical specification proposed by the Wireless Fidelity (WIFI) Alliance is most widely applied, so that a WIFI network usually equals to the IEEE802.11-standard-based WLAN in practice, and under the condition of no confusions, a WIFI module is adopted to describe a WLAN supporting wireless transceiver and processing module in a network node hereinafter.
On such a premise, some operating companies and enterprises have proposed to merge a WLAN and an existing 3GPP network to implement joint transmission and fulfil the aims of offloading and improvement of network performance. Although the 3GPP has formulated a related protocol for interworking of the 3GPP network and the WLAN at present, a current interworking architecture also has some shortcomings, and for example, data stream HandOver (HO) is relatively slower when User Equipment (UE) moves between the 3GPP network and the WLAN, and in addition, data streams of both the networks are required to pass through a network element of a 3GPP core network under such a condition, which may cause a heavier load.
3GPP SA2 adopts an Access Network Discovery Support Function (ANDSF) solution, and provides a mode of selecting a target access network for a terminal according to a policy of an operating company. 3GPP R10 defines an ANDSF standard, and an ANDSF implements intelligent network selection as an access anchor point to implement effective offloading of network access through interactive cooperation of a network and the terminal, and is consistent with an operating direction of multi-network cooperation in the future. The ANDSF formulates a policy on the basis of information such as a network load, a terminal capability and a user subscription condition to help a terminal user to select an optimal network system for access and implement cooperation of multiple access manners. The ANDSF may be deployed independently, and may also be combined with other network elements. At present, the mainstream point of the industry is that the ANDSF may be deployed on Program-Controlled Computer (PCC) equipment.
The ANDSF is a core-network-based WLAN interworking solution, and does not consider influence on an access network, and in addition, the ANDSF is a relatively static solution which may not be well adapted to a dynamic variation condition of a network load and channel quality, so that the 3GPP access network group opens up a discussion about WLAN interworking.
There are three basic candidate access network side solutions for WLAN interworking in a related technology.
Solution 1
A 3GPP access network side provides auxiliary information for UE through a system message or dedicated signalling, and the UE determines how to migrate a service to a WLAN or a 3GPP access network according to the auxiliary information and a rule provided by a network element (such as an ANDSF) except an access network. In the solution, a 3GPP access network and WLAN interworking decision-making entity is located in the UE. Wherein, a content of the auxiliary information includes: a WLAN Received Signal Strength Indication (RSSI) threshold, a Basic Service Set (BSS) load threshold, a WLAN Wide Area Network (WAN) metric threshold, an LTE Radio Access Network (RAN) Reference Signal Received Power (RSRP) or Universal Mobile Telecommunication System (UMTS) RAN Received Signal Code Power (RSCP) threshold, a load level of an LTE/UMTS cell and maximum available idle resources of the LTE/UMTS cell.
Solution 2
A 3GPP access network side provides auxiliary information for UE through a system message or dedicated signalling, the auxiliary information including:
a WLAN RSSI threshold, a WLAN BSS load threshold, a WLAN WAN metric threshold, an LTE RAN RSRP or UMTS RAN RSCP threshold, a load level of an LTE/UMTS cell, maximum available idle resources of the LTE/UMTS cell and an indicator of a service type expected for interworking with a WLAN by the network side.
The 3GPP access network side provides access network selection parameters (priorities of a rule provided by a 3GPP RAN and a rule provided by an ANDSF, selection priorities of the WLAN and the 3GPP RAN, a WLAN interworking decision-making rule and the like) for the UE, and the UE determines how to migrate a service to the WLAN or the 3GPP RAN on the basis of these parameters. In the solution, a 3GPP access network and WLAN interworking decision-making entity is divided into: a 3GPP access network and WLAN interworking rule formulation entity and a 3GPP access network and WLAN interworking process triggering entity. Wherein, the 3GPP access network and WLAN interworking rule formulation entity is located on the 3GPP access network side, and the 3GPP access network and WLAN interworking process triggering entity is located on a UE side. The 3GPP access network side is responsible for formulating a 3GPP access network and WLAN interworking rule, and the UE determines when to trigger a 3GPP access network and WLAN interworking process according to a rule of the 3GPP access network side, and then determines a target access network (the 3GPP RAN or the WLAN) and the service to be migrated in combination with own practical WLAN measurement result and the rule of the 3GPP access network side.
Solution 3
For a terminal in a Radio Resource Control (RRC) connection state (LTE system) or a CELL_DCH state (UMTS), a 3GPP access network side determines a manner for the terminal to migrate a service to a WLAN or a 3GPP RAN, and notifies the terminal of the manner. For a terminal in an RRC IDLE (LTE system and UMTS) or CELL_FACH, CELL_PCH or URA_PCH (UMTS) state, the manner in solution 1 or solution 2 is adopted. In the solution, a 3GPP access network and WLAN interworking decision-making entity is located on the 3GPP access network side, and a UE side has a 3GPP access network and WLAN interworking process triggering entity (enabled only when UE is located in the RRC IDLE (LTE system) or CELL_FACH, CELL_PCH or URA_PCH (UTMS system) state).
The network side is required to transmit measurement configuration parameters of a WLAN interworking mechanism to the UE, including: definition about a triggering event which triggers a WLAN interworking measurement report; a candidate measured WLAN list; and WLAN measurements: a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a BSS load and WAN metrics (including uplink and downlink data rates, load, link state and capacity of the WLAN).
The UE performs WLAN measurement according to the measurement configuration, and reports a measurement result to the 3GPP RAN, and the 3GPP RAN makes a decision about how to perform WLAN interworking according to the WLAN measurement result provided by the UE and own load of the 3GPP RAN.
In the solution, only a basic WLAN interworking flow is defined, a measurement configuration of a WLAN interworking mechanism of a source cell is very likely to be different from a measurement configuration of a WLAN interworking mechanism of a target cell during cell HO or cell reselection of the UE, WLAN measurement performed by the UE during HO/reselection is still performed according to the WLAN measurement configuration of the source cell, and the problem whether the generated WLAN measurement report may be utilized by the target cell or not has yet not been clarified in current standard development.
According to an LTE protocol, UE is required to delete a 3GPP RAN measurement configuration of a source cell after cell HO. The inventor discovers that it may not be so good to continue using such a method for a WLAN interworking mechanism because it may cause problems, and for example, considering that a WLAN target frequency point located in an HO area between two adjacent cells is very likely to exist in WLAN interworking measurement configurations of the two adjacent cells at the same time along with denser and denser distribution of WLAN Access Points (APs), a WLAN measurement result obtained by the UE during HO or reselection of the source cell may have a reference significance for the target cell.
For the problem of how to process a measurement configuration during cell HO or cell reselection in the related technology, there is yet no effective solution.